I guess I'll reply to this, since you wrote a crap tonne there.
But expect it to be all rejected.
First of all, don't take that video seriously with Halo 5 and Haven, that account doesn't even have XBL. It's just a couple of words stuck together.
Getting that tiny detail out of the way, we move to Reach. And it was a good game, in fact I'd say a great game.
Halo shouldn't be stuck in the past, it needs to move on to cater to new fans and stop being a boringly unoriginal game series that it potentially would've declined to. Halo Reach wasn't even remotely bad for a game as a whole. It was well made, quite original and had a powerful team constantly patching it with updates.
Sure it had some problems that were multiplayer breaking, like small glitches, and more commonly known, the insane bloom for the DMR.
I found the Ordnance Drops a neat idea that could've been improved on, but they worked fine enough. If you were skilled enough as a team, the losing team with Ordnance Drops wouldn't be much of a threat, because you have skill to counter it. Gonna make this clear now, I'm not trying to act all tough and MLG, but I easily countered people with powerful Ordnance Drops with most of my loadout weapons. The lack to do that is showing the lack of teamwork and/or skill from the individual. Map control can easily be won with the proper amount of team work and skill, power weapons don't always change the balance of the game.
One thing about sprint is this. Why the hell doesn't a super future soldier not have the ability to run? It literally makes no sense, it should've just been added into the game simply because of that reason. But unfortunately, fans would've not bought the game completely if that reason was given. I don't see how sprint affects the game in a big way, it makes for more opportunities to outplay your opponents, and not being able to counter sprint is a pretty big sign that someone can't play well. Since it's available for all players in Halo 4.
Core experiences are a matter of opinion. I see the core gameplay as this, in one short sentence; Super Soldiers with shields with 2 weapons and grenades pit against others of the same kind. That's literally it, that sums up Halo Multiplayer in a nutshell, everything else are extras.
I haven't played Halo 4 in a while, so I forgot what these hitmakers are, let me know what they are properly if you want. Cause I just can't remember them lol.
Armour Abilites are great in my opinion, with the all time most useless being hologram though. Never liked that poor excuse of an ability. Jetpack barely has an advantage, because when you're in the air, you're just like a duck in England, screwed. Promethean Vision I do agree is a bit overpowered. Sure it's awesome for Flood or something, but on a map like Adrift, it's so damn powerful.
As a whole, I am fine with them staying in the game, I'd be annoyed if AA's are actually removed from the game. Since they bring a new edge to gameplay, and one that works well. Boltshots were bloody easy to counter, I never had problems with them personally, and I barely ever used them because I found them more inefficient than efficient. The high pitch sound and that build up time was more than enough for my to 'nade someone or just run. But that opinion doesn't change when they were nerfed, granted by playstyle doesn't have me going up CQC much.
I will say the Mauler was only ever in 2 games, Halo 3 and ODST, which was built from Halo 3. Having that gun not in that game, really doesn't make any difference at all. 343i needed to make this their own game, they needed their own feel. Which I mainly got from the new style of music composed.
That being said, from the mess they made, 343i openly said many times that they made plenty of mistakes with Halo 4 and thanked everyone for sticking by them to tell them what they did wrong. So they could improve the experience for the next Halo titles they make, assuming the next one will be Halo 5.
343i has listened to the fans since the launch of the game, every update has been decided from votes on waypoint and other places like NeoGaf. 343i continually had new supports to the game to try and fix it, slowly but surely they've fixed multiplayer.
It's still not perfect, but it's nothing like the messiness it used to be at launch.